1. Field of the Invention
The present invention relates to a display device and a method of driving the same. More particularly, the present invention relates to an organic light emitting device and a method of driving the same.
2. Discussion of the Background
A hole-type flat panel display such as an organic light emitting device displays a fixed picture for a predetermined time period, (e.g., a frame), regardless of whether it is a still or motion picture. As an example, when a continuously moving object is displayed, the object moves from a particular position after being at the position for a certain time period of a frame, and is maintained at a new position of a frame for a certain time period before moving again, i.e., movement of the object is discretely displayed. Because the time period of a frame is a time period in which an afterimage is sustained, even if a picture is displayed in this way, movement of an object is continuously perceived.
However, when a continuously moving object is viewed on a screen, because a viewer's eye moves along with the object's movement, which conflicts with a discrete display of the display device, the viewer may see blur on a screen. For example, assume that the display device displays an object that stays at a position A in a first frame and at a position B in a second frame. In the first frame, the viewer's eye moves along an estimated movement path of the object from position A to position B. However, the object is not actually displayed at an intermediate position between position A and position B.
Therefore, because luminance that is recognized by a person for the first frame is a value, i.e., an average value of luminance of the object and luminance of a background that is obtained by integrating luminance of pixels at a path between position A and position B, an object is perceived to be blurred.
In the hole-type display device, because a degree to which the object is perceived to be blurred is proportional to a time period in which the display device sustains the display of the object, a so-called impulse driving method of displaying an image for only some time period and displaying a black color for the remaining time period within a frame has been suggested. In this method, because the time period in which an image is displayed decreases, luminance decreases, so a method of increasing luminance for a display time period or a method of displaying intermediate luminance using adjacent frames instead of a black color has been suggested. However, this method may increase power consumption and complicate driving.
Because a pixel of the organic light emitting device has an organic light emitting element and a thin film transistor (TFT) that drives the organic light emitting element, when the organic light emitting element and the TFT operate for a long time period, estimated luminance may not be displayed due to a change of the TFT's threshold voltage, and when characteristics of a semiconductor that is included in TFTs are not uniform within the display device, a luminance deviation between pixels may occur.